In a charged particle beam device such as an electron microscope and a focused ion beam (FIB) processing device as well as in a freeze drying device, processing and observing of a sample containing moisture, a material susceptible to damage caused by irradiation with an electron beam, and the like are enabled by processing and observing the sample while freezing and cooling, whereby it has been a method widely used in fields such as of biomaterials and organic materials.
In the above-described method, however, since the sample is under a very low temperature, there is a problem of contamination in which carbon or the like within a vacuum device is adsorbed by the sample, and the sample becomes unclean. Thus, it is necessary to prevent the contamination of the sample by providing a cooling part, which has a temperature lower than that of the sample, inside the vacuum device.
One of related arts is disclosed in Japanese Patent Application Laid-Open No. 2010-257617 (PTL 1). For example, it is disclosed in Abstract that “a sample holder for efficiently performing the processing or observation of a sample by means of charged particles while cooling. Particularly, disclosed is a sample holder whereby the processing or observation of a material which may be affected by the influence of heat damage can be performed in a state in which the material is cooled, and furthermore, the influence due to a sample processing method using charged particles can be reduced by cooling. The sample holder is provided with a sample stage capable of fixing a sample piece extracted from a sample by ion beam irradiation, and a rotation mechanism for rotating the sample stage in a desired direction, which can be attached to an ion beam device and a transmission electron microscope device, and which has a movable heat transfer material for thermally connecting the sample stage and a cooling source, and an isolation material for thermally isolating the sample stage and the heat transfer material from the outside. According to the sample holder, the processing or observation of a sample by means of charged particle beams can be performed while efficiently cooling.”
Another related art is disclosed in Japanese Patent Application Laid-Open No. 2000-277045 (PTL 2). For example, it is disclosed in Abstract that “PROBLEM TO BE SOLVED: To simplify the structure of a cryostage for observing sample freezing, and to attain the miniaturization thereof by arranging a cooling member near a sample so that a part of any one of a sample table, a sample holder and a sample stage contacts with the cooling member arranged between an objective lens and the sample. SOLUTION: In order to reduce the gas molecule near a sample surface while adsorbing the residual gas molecule and prevent the sample pollution, a cold cooling plate 16 (anti-contamination trap) is arranged between a lower part of an objective lens 8 and a sample 9. A fitting 21 as a structural member of a stage 20 and having heat conductivity in relation to the sample 9 is made to contact with the cooling plate 16 so as to cool the sample 9 placed on a sample table 19. A temperature sensor such as a thermo-couple 22 and a heating heater 23 are arranged in a heat conductive passage, and the heating heater 23 is controlled on the basis of the temperature information from the thermo-couple so as to control the temperature of the sample 9.”
Still another related art is disclosed in Japanese Patent Application Laid-Open No. 2007-53048 (PTL 3). For example, it is disclosed in Abstract that “PROBLEM TO BE SOLVED: To provide a processing device using a focusing charged particle beam which can cool a test piece rapidly and can improve processing precision by reducing thermal drift. SOLUTION: A test piece which is observed and processed by the focusing charged particle beam is made minute and only the minute test piece is locally cooled. Otherwise, a test piece installing part which has a structure capable of attenuating thermal drift is used.”